dbp-icon: Add a icon name mapping

We don't want to depend on one particular icon set and define our own, so we can more easily switch in the future.

This means we need to following:

• A whitelist of names, unknown names should error out
• Names should be named according to their usage, not how they look like. This means there can be multiple different names for the same icon in an icon set, if the icon happens to be usable in multiple places
• We should also add all the names and examples to the demo page

The Library App uses these icons:

component = file	line	icon name
vpu-library-app.js	304	chevron-up
vpu-library-app.js	304, 580	chevron-down
vpu-library-app.js	584	close
vpu-auth.js	383	chevron-up
vpu-auth.js	383, 402	chevron-down
vpu-library-book-offer-select.js	359	reload
vpu-person-select.js	339	reload
vpu-common-demo.js	117, 118, 119	cloudnetwork

added 1 deleted label

added To Do label

changed title from vpu-icon: Add a icon name mapping to dbp-icon: Add a icon name mapping